This invention concerns a synthetic crimped continuous filament (BCF) yarn which has been precolored or can been differentially dyed to produce a novel heather appearance.
As is known in the art, a heather appearance includes small points of individual color, i.e., color points, randomly distributed throughout a matrix of contrasting colors. Heather BCF yarns can be made from differentially dyeable or precolored BCF component yarns in various ways to provide a variety of heather appearances. These heather appearances can range from a very bold heather with relatively large random sections of individual color, to a very fine heather having a high degree of yarn-to-yarn filament commingling between the components.
In the yarn processing art, there are two known basic yarn structures. One yarn structure characterized by loops and a continuous tangle of individual filaments, such as shown in U.S. Pat. No. 2,852,906, is referred to as "air jet textured" or "bulked". This first yarn structure shall be referred to as "textured" within this description.
The second basic structure contains nodes or densely entangled sections separated by bulkier non-entangled sections, such as shown in U.S. Pat. No. Re. 31,376. The nodes are referred to as "intermingled", that is, entangled without forming loops. These nodes are also referred to in the art as "compacted". Yarns with compacted nodes and bulkier non-entangled sections are referred to herein as "interlaced". "Commingling" refers to filament blending between different yarns. The densely entangled nodes of the second yarn structure prevent commingling with another yarn.
The patent to Nelson, U.S. Pat. No. 4,343,146, discloses a process for producing heather BCF yarns in which a first yarn is entangled with at least one second yarn which is precolored or differentially dyeable with respect to the first yarn and which contains frequent periodic short relatively compact nodal regions of high-filament entanglement. When the first and second yarns are textured according to the described Nelson process, the nodal regions of the second yarn are substantially free from commingling with filaments of the first yarn, and the nodal regions are separated by bulkier relatively open regions of fully textured first and second yarns. The Nelson '146 patent describes known prior art jet entangling or interlacing procedures to produce the color-point second yarn having periodic nodal regions.
Due to the high popularity of BCF heather yarns in the tufted carpet market, distinctive novel heather effects are in high demand. However, as the Nelson reference acknowledges, the preparation of acceptable new yarns has remained difficult due to the necessity of combining the component yarns in a sufficiently random yet consistent manner to obtain a distinctive and desirable heather appearance. Much of the difficulty in producing distinct BCF heather yarns is the need to prevent the formation of directional carpet appearance or patterns, such as streaks and chevrons in the finished product. Prior jet interlacing processes as described in the Nelson '146 patent, frequently rely upon multiple tensions applied to the yarn components, which tensions tend to vary over time, requiring constant attention to the tensioning mechanisms. In addition, if it is desired to vary the tensions on the several components to cause multiple colors to stand out randomly, making these tension changes quickly enough to prevent directional carpet appearance is extremely difficult.